The present invention relates to gas lighters of the xe2x80x9croll and pressxe2x80x9d type, and more specifically to child resistant lighters.
Roll and press gas lighters of the type used for lighting cigarettes are well known. A lighter of this type has a gas reservoir, a gas regulation system including a valve opened and closed by a lever, and a wheel ignition mechanism. The ignition mechanism preferably comprises a spark-wheel disposed midway between two thumb-wheels of larger diameter than the spark-wheel. The spark-wheel rubs frictionally against a flint when rotated, in order to project sparks above the opened burner and ignite the gas, producing a flame. Such lighters are often provided with a cap or shield around the fuel jet with a tongue passing over the spark-wheel in order to avoid the user""s thumb becoming soiled with flint dust.
It is important to prevent the use of such lighters by children under the age of 5 years. The standard for child resistance has been specified in the USA by means of a functional test by the Consumer Product Safety Commission: 16 CFR Parts 1145 and 1210, Risks of Injury Associated with Lighters That Can Be Operated by Children: Safety Standard for Cigarette Lighters; Rules: Federal Register, Monday Jul. 12 1993. The degree to which a lighter is child resistant may be objectively determined by applying the test described in these Rules and Regulations.
Many child resistant lighter mechanisms have been proposed. There are two broad techniques for child resistance. Most systems use a lever mechanism having two positions; one where the mechanism is prevented from working (the lighter cannot function properly), and a second where the mechanism is manipulated (by displacement, pivoting, etc) to a position where the lighter can function and produce a flame. The mechanism must reset automatically to its original xe2x80x9csafexe2x80x9d position after the lighter has been used. In the other type of mechanism, the unlocking system is in the wheel assembly area in order to minimize the time the user takes to learn how to operate it. Usually, the mechanical interlocking means as described above involve properties or parts which make operation of the lighter difficult for children while remaining easy for adults.
An example of the latter type of system is described in WO 95/04247, BIC. In this patent, there is a resilient blade or guard mounted around the spark-wheel to prevent the access of the thumb to the wheel assembly unless the user presses downwards hard enough to depress the blade below the level of the thumb-wheels. Depending on the height of the blade, using this lighter is more or less uncomfortable for the user, and care must therefore be taken to ensure that the blade characteristics are maintained within an acceptable range during production. Furthermore, the protruding blade is vulnerable to removal by the user with an external tool such as a screwdriver.
FR A-2417722 discloses a guard or blade member which extends over the spark wheel to improve the aesthetic appearance and to protect the top part of the lighter. It also prevents contact of the user""s thumb with the spark wheel which may cause the thumb to become dirty.
FR 95 08011 to the present applicant discloses a child resistant lighter whose thumbwheels are provided with smooth edges, requiring a greater pressure from the user""s thumb to operate the lighter than can be exerted by a child.
Lighters are typically manufactured in very large numbers, and it is important that the degree of child resistance, and hence the degree of difficulty which the adult user will experience in using the lighter, should be maintained within closely defined limits for each unit produced.
However, the prior art methods described above do not readily admit of fine adjustment of the degree of child resistance during prototyping and production. It is difficult to accurately and economically control and adjust the resilience of a stamped or pressed metal strip or the frictional characteristics of the smooth periphery of a thumbwheel, and it is therefore difficult to accurately specify the degree of child resistance by reference to these characteristics.
The object of the present invention is to provide an improved gas lighter which offers a consistent and reliable combination of child resistance with ease of use by the adult user.
Accordingly the present invention provides a child resistant lighter of the roll and press type including a wheel assembly having a spark wheel and thumbwheel means, and further including a shield having a protective strip around the wheel assembly and interacting therewith to make the wheel assembly difficult for children to rotate, characterized in that the wheel assembly is resiliently mounted for downward movement so that the user has to press the wheel assembly downwards before it can be rotated.
The present invention, in its preferred embodiment, provides a child resistant lighter which can be conveniently operated and which requires no significant learning effort on the part of the user, and in which the possibility of inadvertent ignition other than by the correct specified method is small.